Hi all,
With phase 1 of SAI wrapping up, I’d like to start the ball rolling on aligning around phase 2 features.
In particular, we need to nail down the syntax for doing non-exact string matches. We have a proof of concept that includes full Lucene analyzer and filter functionality – just the text transformation pieces, none of the storage parts – which is the gold standard in this space. For example, the StandardAnalyzer [1] lowercases all terms and removes stopwords (common words like “a”, “is”, “the” that are usually not useful to search against). Lucene also has classes that offer stemming, special case handling for email, and many languages besides English [2].
What syntax should we use to express “rows whose analyzed tokens match this search term?”
The syntax must be clear that we want to look for this term within the column data using the configured index with corresponding query-time tokenization and analysis. This means that the query term is not always a substring of the original string! Besides obvious transformations like lowercasing, you have things like PhoneticFilter available as well.
Here are my thoughts on some of the options:
`column = term`. This is what the POC does today and it’s super confusing to overload = to mean something other than exact equality. I am not a fan.
`column LIKE term` or `column LIKE %term%`. The closest SQL operator, but neither the wildcarded nor unwildcarded syntax matches the semantics of term-based search.
`column MATCHES term`. I rather like this one, although Mike points out that “match” has a meaning in the context of regular expressions that could cause confusion here.
`column CONTAINS term`. Contains is used by both Java and Python for substring searches, so at least some users will be surprised by term-based behavior.
`term_matches(column, term)`. Postgresql FTS makes you use functions like this for everything. It’s pretty clunky, and we would need to make the amazingly hairy SelectStatement even hairier to handle “use a function result in a predicate” like this.
`column : term`. Inspired by Lucene’s syntax. I don’t actually hate it.
`column LIKE :term:`. Stick with the LIKE operator but add a new symbol to indicate term matching. Arguably more SQL-ish than a new bare symbol operator.
-- 